U.S. Pat. No. 5,046,857, issued 10 Sept. 1991 and assigned to the assignee of this invention, describes a thermal probe assembly having a premolded unitary one piece plastic shell which attaches to a structural member, e.g. a plastic intake manifold of an internal combustion engine, through male screw threads on the shell and female screw threads in a socket on the manifold. Manufacturing costs associated with fabricating male and female plastic screw threads are relatively high. A twist lock according to this invention for attaching a plastic shell of a thermal probe to a plastic structural member such as an internal combustion engine intake manifold is an improvement relative to the thermal probe attachment described in the aforesaid U.S. Pat. No. 5,046,857.